Paper making pulp refiner



Dec. 22, 1964 J. BAXTER, JR 3,162,385

PAPER MAKING PULP REFINER Filed Feb. 14, 1961 2 Sheets-Sheet l FIG-1 INVEN TOR.

JOSEPH BAXTER,JR

ATTORNEYS Dec. 22, 1964 J. BAXTER, JR 3,162,385

PAPER MAKING PULP REFINER Filed Feb. 14, 1961 2 Sheets-Sheet 2 FI-6 3 I FIG-7 76 75 s ez fifim 70 \&

INVENTOR.

JOSEPH BAXTER, JR.

ATTORNEYS Patented Dec. 22, 1964 Ohio Filed Feb. 14, 1961, Ser. No. 89,281 9 Claims. (Cl. 241-163) This application relates generally to refining apparatus for use in the preparation of paper making stock, and more particularly to apparatus for effecting defibering of paper making pulp prior to the final refining thereof.

The invention is particularly concerned with the treatment of pulp which still contains lumps or bundles of fibers, such as defibered chips, pulp laps, waste papers and the like, and which therefore requires separation mto individual fibers before it can properly be treated in a Jordan or similar refiner for developing desired fiber characteristics.

It is a primary object of the invention to provide rotary refining apparatus of novel construction for paper making pulp as outlined above which is capable of efiecting complete defibering in a single pass of the pulp therethrough with minimum possibility that any lumps or bundles can slip through without being defibered.

It is particularly an object of the invention to prov de refining apparatus having the above characteristics which is of such construction that multiple separate refining zones are established therein in stepped relation from the standpoint of refining action such that the entering lumps or bundles of fibers are progressively reduced in size by the diiferent zones or stages of progressively more severe defibering action.

Another object of the invention is to provide refining apparatus as outlined above which is of outstanding simplicity and economy of construction, especially with respect to the refining elements which perform the defibering action therein.

An additional and more specific object of the invention is to provide refining apparatus for the purposes outlined above wherein there is a rotor and a stator or shell which carry a plurality of rows of substantially matching or complementary teeth, such as external and internal gear teeth respectively, arranged with relatively slight radial clearance to define a corresponding plurality of working zones, and which rows of teeth are progressively finer from the inlet to the outlet of the shell so that each pair of rows has a greater number of teeth therein than the preceding pair to provide correspondingly more intense de fibering action on the stock passing therebetween.

It is a further object of the invention to provide refining apparatus as outlined in the preceding paragraph wherein each pair of rows of teeth not only has a greater number of teeth therein than the preceding pair of rows toward the inlet of the shell, but also each pair of rows is of greater diameter than the preceding pair to produce a correspondingly increased peripheral speed of the rotor teeth in each refining zone from the inlet of the shell to its outlet.

Additional objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings-- FIG. 1 is a side elevational view of refining apparatus constructed in accordance with the invention;

FIG. 2 is an end elevation look-ing from right to left in FIG. 1;

FIG. 3 is an enlarged fragmentary section on the line 3--3 of FIG. 2;

FIG. 4 is an enlarged fragment of FIG. 3 showing the several refining zones in the apparatus of FIGS. 1-3;

FIG. 5 is an enlarged fragmentary section on the line 5-5 of FIG. 4 showing the teeth in the first and least severe refining zone;

FIG. 6 is a section similar to FIGS on the line 6-6 of FIG. 4 showing the teeth in the first intermediate refining zone;

FIG. 7 is a section similar to FIG. 5 on the line 7--7 of FIG. 4 showing the teeth in the second intermediate refining zone; and

FIG. 8 is a view similar to FIG. 5 on the line 8-8 of FIG. 4 showing the teeth in the last and most severe refining zone.

Referring to the drawings, which illustrate a preferred embodiment of the invention, the main body of the refiner comprises a lower body section 10 and an upper body section 11 which define a generally cylindrical chamber open at one end thereof, and this open end is substantially closed by an annular packing box 12 through which a drive shaft 13 projects into the interior of the refiner body. The shaft 13 is supported exteriorly of the refiner body by suitable bearings within bearing housings 15 and 16 and a housing spacer 17, all of which are in turn supported on a bearing support frame 20 bolted or otherwise secured to the body section 10 and packing box 12.

A tangentially arranged inlet port 22 leads into the inlet chamber 23 within the refiner body 10-11, and a tangentially arranged outlet port 24 leads from the outlet chamber 25 at the opposite side of the refiner body from the inlet port 22. There is a similar tangentially arranged port 26 opposite the inlet port 22 which forms a trap for tramp metal and is provided with a siutable clean-out door assembly indicated generally at 27. Access to the inlet chamber 23 is also available through a port 28 in the upper body section 11 which is normally closed by a flange 29 as shown.

The inlet chamber 23 and outlet chamber 25 within the refiner body are separated by the relatively rotating rotor and stator which define the stepped refining zones in which pulp is defibered as it passes from the inlet chamber 23 to the outlet chamber 25. The stator or shell is indicated generally at 30 and is a separately formed part which is removably supported within an annular flanged boss formed by complementary parts 31 and 32 of the body sections 10 and 11 respectively. The shell 30 is secured against rotation by a key 33 and cooperating keyway 34 as shown in FIG. 3, and it is held axially in position by a half ring 35 which is secured to the boss section 32 by a screw 36 and by similar screws 37 to the shell 30 itself.

The rotor assembly is indicated generally at 40 and includes a hub 41 which is preferably keyed on the tapered end of the shaft 13 and is held axially in position by the cap 42 bolted to the end of the shaft 13. The rotor hub 41 carries the rotor 44 which is an annular body secured on the hub 41 as shown by means of the clamp ring 45 and bolts 46.

The shell 30 and rotor 40 are each provided With a plurality of circumferential rows of respectively inner and outer teeth of diiferent sizes, spacing and radius which thus define a series of stepped refining zones of progressively more severe action on the pulp as the stock passes from the inlet chamber 23 to the outlet chamber 25. In the unit shown in FIGS. 3 and 4, there are four of these stepped refining zones identified as AD respectively in FIG. 4, and the teeth which define the individual zones are shown in enlarged detail in FIGS. 5-8 as now described.

FIG. 5 shows the first refining zone A entered by the stock from the inlet chamber 23, and in accordance with the invention the refining action in this zone is relatively gentle. The portion of the rotor 40 in this zone is provided with a plurality of relatively coarse teeth each of which has a radially outer surface 51 of substantial area, these surfaces 51' being cylindrically curved aboutv the center of the rotor 40; The teeth 50 are separated by grooves 52 roughly complementary in individual radial section to the teeth themselves so thateachjgroove has .a generally flat bottomsurface 53. i f I The shell 30 is provided with a row of internal teeth 55 in the zone A which are approximately complementary in section to the teeth 50 in that: the dimensionsof'their radially inner surfaces 56 are-approximately equal, to the corresponding dimensions of the rotor teeth surfaces51.

There are the same number of shell teeth 55 as thereare' rotor teeth50 so that-there are similar-grooves 57 there between, each of these grooves having a' substantially xfla't bottom 58; By way-of illustrativecexample, in one satisfactory embodimentof the invention, there are forty-eight teeth 50 having an 'outer radius of approximately'7 inches and also forty-eight teeth 55, and their res'pectivedimem 4. in number to the rotor teeth 70, and the dimensions of their radially inner surfaces 76 substantially match those of the tooth surfaces 71. Satisfactory results have been obtainedwhen in the assembled relation of the rotor and shell, the spacing between the surfaces 71 and 76 is of the order-of .060 inch. a a I 1 FIG. '8 illustrates the teeth which vform'the last refining zone D wherein the most severe defibering action occurs.

The teeth 80 are similar to the other rotor teeth, having similar outer surfaces 81, but these teeth'80 are the smallest on the rotor and are set-on the largest radius, for example a radius approximately .360 inch greaterthan that of the tooth surfaces '71fand with the groove bottoms- 83 approximately .1 25 inchfgreater in radius than the sions are such that whenthe rotor and shell are assembled," u

there is a radial spacing of the order of the teeth surfaces 51 and 56.; e

.150 inch between FIG. 6 illustrates the teeth which form the refining zone B next to the zone A, and these teeth are proportioned toprovide a somewhat more severe refining action; The

rotor teeth 60 are similar to the teeth50, and they have similar radially outer surfaces 61. and are separated .by grooves 62 having fiat bottoms 63. The teeth 60, however, areof individually smaller radial dimensions and are formed on a somewhat greater radius than the teeth a a 50. Preferably this radius. difli'erenceis such that the groove bottoms 63 are spaced radially beyond the tooth surfaces 51, and satisfactory results have been obtained with thisradius difference being of the. order of .365 inch.

These differences in proportions and radius also make it possible to provide a substantially greater number of teeth- 60 than teeth 50, and satisfactory results have been ob tained with a rotor having sixty-four teeth 60 as compared with forty-eightteeth 50. 'Also, it will be noted tooth surfaces 71. This. makes itpossible' to have a still greater number of teeth S01han teeth 70, andsatisfactory results have been obtained with ninety-six teeth 80 when the numbers and dimensions of the other teeth are as previously noted. V I f '5 The complementary shell teeth 85 are equal in number to the rotor teeth-80v and have a radially inner surface 86 substantially matching the 'rotor teeth surfaces 8 1., In the assembled relation of the ,rotor and stator, satisfactory resultshave been obtained with these teeth surfaces of the .order of .063 inch apart. 7 It will 'also be seen that the progressive reduction in dimensions'of each set of teeth correspondingly'reduces the radial depth of the grooves therebetween, for examplefrom a maximum of .524 inch and .536 inch for the grooves ,52 and 57 to a minimum of .234 inch' and .266inch for "the grooves 82 and .87 respectively.

In operation with the apparatus constructed as disclosed, thestock comprising the pulp to be defibered en-' ters the inlet chamber 23 tangentially to produce an inithat the stator teeth 55 extend radially'inwardly beyond u faces 61. Preferably the radial spacing between the tooth surfaces 61 and 66 should bejless than that between the surfaces 51 and 56, and satisfactory results'have been ob: tained witha .spacing of the order of .063 inch. ,It will be seen that the greater number of teeth 60 and 65i,to-'

gether' "withtheir greater radii than, the teeth 50 and' 55 will' cause a substantially greater tooth speed asiwell as in the number of passesof tooth surfaces 61 with respect to each tooth surface 66. This result together with the closer spacing of the teeth 60 and 65 will produce'a substantially more severe refining action on thepulp than in the zone 'A defined by the teeth 50-55. l p 1 FIG. 7 illustrates the teeth which form thenext intermediate refining zone C downstream .from the zone B. As shown, f'the rotor teeth 70 are substantially smaller than the rotor teeth 60, and each tooth 7 0' has a radially outer surface 71 of substantial dimensions which, however, are' somewhat less/than the idimensions of the surfaces 51 and 61. Alsothe teeth 70" are formed on a tial circulatory motion "therein, and it is discharged through the outlet port 25 after passing through the successive refi ning zones defined by the teeth ofthe rotor and shell. j As noted, the teeth in each successive zone are progressively smaller and more closely spaced to pro-' duce a correspondingly progressively more severe refining action in each zone. Thus, with twice. as many teeth in the final zone D as in the initial zone A, thechips or particles offiber'are broken down "into smaller sizes as they pass through successive; zones until they are substantially completely defibered before they leave the final zone D.

' One of the major advantages of the operation of the apparatus of the'inventionderivesfrom the fact that its construction effectively inhibits the possibility of large chips or particles slippingthrough without effective defiber'ing. For example, if defibering-is done according to conventional practice bymeans of a conventional Jordan, it is possible for some large particles to be channeled completely through the Jordan byway of, the grooves between the plug and shell bars and thus .never be subjected to mechanical action. In the apparatus of the invention, such result is prevented'by a number, off-actors. One is that the grooves between the teethin each successive'zone are progressively smaller. Another'is the arrangement of adjacent rows of teeth with each row of shell teeth greater radius thanthe teeth'fitl fonexample .a radiusfor J the groove bottoms 73 whichisfapproximately .220. inch greater than that. of the tooth fsurfaces, 61, andalso a" radiusfor the surfaces 71 which .is at least .030 inch greater than that of the .shell groove-bottoms 68.1 With sixty-four teeth 60 and the other dimensions as previously.- stated, satisfactoryresults have been obtained'with'eighty' teeth 70..

The complementary :shell 7 teeth I 5 in FIG. 17 are equal a through channel available to largeparticles.

radially overhanging theentrances to. the grooves between the adjacent rotor tooth on the downstream side so that these grooves in the lower teeth are successively swept acrossthe end faces of the shell teeth and there is never Stillanother factor contributing to this resultas well asgenerally effective defibering is that there is an abrupt change in circumferential speed from zone to zone, .due to the progressively greater-diameters of' the rotor across each successive row of rotor teethi Theapparatus .of-the invention also offers substantial advantages. from thelstandpoint of ease of manufacture and maintenance.

Thus the parts of therotor and shell -.which include the teeth are readily producedby convento employ rotor and shell assemblies of different sizes in the same body, depending upon the capacity desired in the finished unit. Maintenance is extremely simple, particularly the exchange of the rotorand shell when replacement is required. It is merely. necessary to remove the upper body section 11, which may conveniently be done by means of the eye-bolt 90, and the shell 30 can be similarly removed by simply releasing the screws 37 and then sliding the shell into the inlet chamber 23 free of the rotor. The rotor assembly 40 can then be similarly removed after releasing the bolts 46, and replacement of the new rotor and shell will follow the reverse steps. Note that with the construction of the body as shown, no extra space is needed beyond either end of the apparatus in which to carry out replacement operations as is the case with a Jordan.

A further practical advantage of the apparatus of the invention lies in the fact that the parts are automatically assembled into proper working relation and are not subject to adjustment. It is therefore assured that the apparatus will at all times operate in the manner for which it was designed and that its intended operating conditions cannot be altered by unauthorized adjustment such as can occur in the case of a Jordan or other refiner wherein the spacing of the relatively moving working parts can be adjusted during operation. It will be seen that this advantage is related to the ease of replacement of worn working parts as already discussed, since it is then more desirable to install a new rotor and shell than to attempt to renovate worn parts by adjustment or the like.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may. be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. Refining apparatus of the character described for liquid slurry stock, comprising a shell defining a refining chamber, means in said shell forming an inlet chamber and an outlet chamber on opposite sides of said refining chamber, a rotor mounted for rotation in said shell and including a rotor body extending through said refining chamber, said rotor body having thereon at least two circumferential rows of substantially uniform and uniformly spaced teeth forming working surfaces, said teeth in said row nearest said inlet chamber being of substantially greater depth and spacing than said teeth in said row nearest sai outlet chamber to provide a correspondingly greater number of teeth in said row nearest said outlet chamber, said shell having thereon rows of teeth substantially complementary to and in radially spaced and overlying relation with said teeth on said rotor body to define therewith a correspondingly plurality of stepped working zones for the stock passing from said inlet chamber to said outlet chamber, and said teeth and the grooves therebetween in each of said rows extending substantially parallel with the axis of rotation of said rotor to minimize the pumping action of said apparatus and to effect a substantially uniform rate of axial travel of the stock with respect to each of said zones.

2. Refining apparatus of the character described for liquid slurry stock, comprising a shell defining a refining chamber, means in said shell forming an inlet chamber and an outlet chamber on opposite sides of said refining chamber, a rotor mounted for rotation in said shell and including a rotor body extending through said refining chamber, said rotor body having thereon at least two circumferential rows of substantially uniform and uniformly spaced teeth forming working surfaces, said rotor being of lesser diameter across the first said row of teeth adjacent said inlet chamber than across the last said row nearest said outlet chamber, said teeth in said first row being of substantially greater depth and spacing than said teeth in said last row to provide a correspondingly greater number of teeth in said last row, said shell having therein rows of teeth substantially complementary to and in radially spaced and overlying relation with said teeth on said rotor body to define therewith a corresponding plurality of stepped working zones for the stock passing from said inlet chamber to said outlet chamber, and said teeth and the grooves therebetween in each of said rows extending substantially parallel with the axis of rotation of said rotor to minimize the pumping action of said apparatus and to effect a substantially uniform rate of axial travel of the stock with respect to each of said zones.

3. Refining apparatus of the character described for liquid slurry stock, comprising a shell defining a refining chamber, means in said shell forming an inlet chamber and an outlet chamber on opposite sides of said refining chamber, a rotor mounted for rotation in said shell and including a rotor body extending through said refining chamber, said rotor body having thereon at least two circumferential rows of substantially uniform and uniformly spaced teeth forming working surfaces, said teeth in the first said row nearest said inlet chamber being of substantially greater depth and spacing than said teeth in the last said row nearest said outlet chamber to provide a correspondingly greater number of teeth in said last row, said shell having therein rows of teeth substantially complementary to and in radially spaced and overlying relation with said teeth on said rotor body to define therewith a corresponding plurality of stepped working zones for the stock passing from said inlet chamber to said outlet chamber, said teeth and the grooves therebetween in each of said rows extending substantially parallel with the axis of rotation of said rotor to minimize the pumping action of said apparatus and to effect a substantially uniform rate of axial travel of the stock with respect to each of said zones, and said teeth in at least one of said sets of complementary rows being of different axial length from said teeth in another of said sets of complementary rows to provide correspondingly different dwell times for the stock in the respective said working zones.

4. Refining apparatus of the character described for liquid slurry stock, comprising a shell defining a refining chamber, means in said shell forming an inlet chamber and an outlet chamber on opposite sides of said refining chamber, a rotor mounted for rotation in said shell and including a rotor body extending through said refining chamber, said rotor body having thereon at least three adjacent circumferential rows of substantially uniform and uniformly spaced teeth forming working surfaces, said teeth in the first said row nearest said inlet chamber being of maximum depth and spacing with respect to each of the other said rows, said teeth in each other said row being of progressively lesser depth and spacing with respect to said teeth in said first row to provide a correspondingly greater number of teeth in each of said rows progressively from said inlet chamber to said outlet chamher, said shell having therein rows of teeth substantially complementary to and in radially spaced and overlying relation with said teeth on said rotor body to define therewith a corresponding series of stepped working zones for the stock passing from said inlet chamber to said outlet chamber, and said teeth and the grooves therebetween in each of said rows extending substantially parallel with the axis of rotation of said rotor to minimize the pumping action of said apparatus and to effect a substantially uniform rate of axial travel of the stock with respect to each of said zones.

5. Refining apparatus of the character described for liquid slurry stock, comprising a shell defining a refining chamber, means in said shell forming an inlet chamber and an outlet chamber on opposite sides of said refining chamber, a rotor mounted for rotation in said shell and including a rotor body extending through said refining chamber, said rotor body having thereon at least three adjacent circumferential rows of substantially uniform and uniformly spaced teeth forming Working surfaces, the

diameter of said rotor body across succe'ssive saidrows' vof teeth being progressively greater from said inlet cham-' ber to said outlet chamber, said teeth in the fi'rstsaid row nearest'sai'd inlet chamber being of maximum depth and spacing with respect to each of the other said rows, said teeth in each other said row being of progressively I shell' teeth: having a radially inner surface approximately lesser depth and spacing with respect to said teeth .said first row to provide'a correspondingly greater number of teeth in each of said rows progressively from said inlet chamber to said outlet chamber, said shellh'aving therein rows of teeth substantially complementary to and 'in' radially spaced and overlying relation with said teeth on said rotor body todefine therewith a corresponding series of stepped working zones for the stock'pa'ssing from said inlet chamber to said outlet chamber, and said teeth and the grooves therebetween in each of'said'rows extend: ing substantially parallel with the axis of rotation of said rotor to minimize 'the pumping action of said. apparatus and to effect a substantially uniform rate of axial travel of the stock with respect to each of said zones.

6. Refining apparatus of the character 'fiescribed for liquid slurry stock, comprising a shelldefining a refining chamber, means in said shelliforming an inletchamber and an outlet chamber on opposite sides ofsaid refining equal in the circumferential dimension thereof to each of the adjacent 'rotor"teeth'-'to; provide working surfaces on said shell teeth of substantially the same areas as said workin'g'surfaces on said rotor teeth, adjacent teeth in each said row, of shell teeth being separated from each other "by a groov'e, which is jroughlycomplementary in radial sectionto said adjacent shell teeth,,'each of said teeth and each of said grooves extending substantially parallel with the of "rotation of said rotorand being of substantially uniform radial dimensions toelfect a substantially uniformrate' of travel jof: the stock along'each of said grooves.

' Y "SIIRefining -apparatus ofvthe charactendescribed for chamber, a rotor mounted for rotation in said shell 'and;

including a rotor body extending :through' said refining chamber, said rotor body havingthereon at least three adjacent circumferential rows of substantially uniform and nearest said inlet chamber being of maximum depth and spacing with respect to each *of the other said rows, said teethtin each other said row being of progressively lesser depth and spacing with respect to said teeth in said first "liquid slurry stock, 'comprising'a shell defining arefining chamber, means in said shell forming an inlet chamber and an outlet chamber on opposite sides of said refining chamber, a rotor mounted for rotation in said shell and including a rotor bodyv extending through said: refining chamber, said rotor body having thereon at least two circumferential rows of substantially uniform and uniform'ly spaced teeth, each of said teeth having a radially outer surface of a substantial circumferential dimension fdefining a Working-surfaceof correspondingly substantial :area, adjacent teeth in each said row being separated from "each other by'a groove which is roughly complementary in'radial section vto eachof the teeth in said row, said rotor being of lesser diameter across the first said row of teeth adjacent 'said inlet chamber than across the last said row nearest said outlet chamber, said teeth in said first row being of substantially greater depth and spacing than said teeth in said last'row to provide a correspondingly greaternumberof teethin said last row, said shell having therein'rows of teeth substantially complementary to rowto provide a correspondingly greater number of teeth I in each of said rows progressively from said inlet chamber to said outlet chamber, and said shell having therein rows of teeth substantially complementary tow and in radially spaced and overlying relation-with said teeth on said rotor body to define therewith a corresponding'series of stepped working zones for the stock passing from said inlet: chamber to said outlet chamber, said teeth and the grooves therebetween in each of'said rows extending substantially parallel with the axis of rotation of said rotor to minimize the pumping action of said apparatus and to eifect a substantially uniform rate of axial travel of the stock with respect to each of said zones, and said teeth:

in each said row in said shell extending radially inwardly in completely overlapping relation with saidteeth in the adjacent row downstream therefrom on said rotor and with the spaces between adjacent said rotor teeth. 7 V

7. Refining apparatus of the character described for liquid slurry stock, comprising a shell defining a refining chamber, means in said shell forming an inlet chamber defining a working'surface of correspondingly substantial and 'in* radiallyispaced' and overlying relation with said teeth on said rotor body to'define therewith a corresponding plurality'ofr stepped working zones forthe stock passing fromsaid inlet chamber to said outlet chamber,

and each of said shell'teeth having a radially inner surfaceapp'roximately, equal in the circumferential dimension thereof 'to each of the adjacent rotor teeth to'provide working surfaces on said shell teeth of substantiallythe same areas as: said working surfaces on said rotor teeth, adjacent teeth in each said row of shell teeth being separated from each other. by a groove which is roughly "complementary in radial section to said adjacent shell teeth, each of said teeth'andeach of said grooves extending substantially parallel with the axis of rotation of said rotor and beingof substantially uniform radial dimensions along each of. said grooves a t 9. Refining apparatus of the character described for to effect a substantially uniform rate of travel of the stock Y liquid slurry stock, comprising a shell defining a refining area, adjacent teeth in each said row being separated from 7 each other by a groove which is roughly complementary chamber, means in said shell'forming an inlet. chamber and an'outlet chamber on opposite sides of said refining chamber, a rotor mounted for rotation-tin said shell and including a rotor body extending through said refining chamber,-said rotor body having thereon at least three adjacent circumferential rows of substantiallybniform and uniformly spaced teeth, each of said teeth having a radially outer surface of a, substantial circumferential dimension defining a Working surface" of correspondingly substantial area, adjacent teeth in each said row being separated from each other b'y-a groovewhich isroughly complementary in radial section to each of the teeth in s'aid row, the diameter of said rotor body across successive said rows of teeth being progressively greater from ,said inlet chamber -to said outletchamber, said teeth in the first said row nearest said inlet chamber beingof,

maximum depth and spacing with respectto each of the othersaid rows, said teeth'in each other'said row being of progressively lesser depth and spacing with respect to 9 said teeth in said first row to provide a correspondingly greater number of teeth in each of said rows progressively from said inlet chamber to said outlet chamber, said shell having therein rows of teeth substantially complementary to and in radially spaced and overlying relation with said teeth on said rotor body to define therewith a corresponding series of stepped working zones for the stock passing from said inlet chamber to said outlet chamber, and each of said shell teeth having a radially inner surface approximately equal in the circumferential dimension thereof to each of the adjacent rotor teeth to provide working surfaces on said shell teeth of substantially the same areas as said Working surfaces on said rotor teeth, adjacent teeth in each said row of shell teeth being separated from each other by a groove Which is roughly complementary in radial section to said adjacent shell teeth, each of said teeth and each of said grooves extending substantially parallel with the axis of rotation of said rotor and being of substantially uniform radial dimensions to effect a substantially uniform rate of travel of the stock along each of said grooves.

References Cited in the file of this patent UNITED STATES PATENTS 368,710 Fredericks Aug. 30, 1887 794,187 Pfeiffer July 11, 1905 1,523,478 Fischer Jan. 20, 1925 1,593,854 Snyder July 27, 1926 1,941,770 Welsford Jan. 2, 1934 2,278,051 Ambrose Mar, 31, 1942 2,484,509 Hopkins Oct. 11, 1949 2,824,500 Cumpston Feb. 25, 1958 2,888,213 Hubner May 26, 1959 

1. REFINING APPARATUS OF THE CHARACTER DESCRIBED FOR LIQUID SLURRY STOCK, COMPRISING A SHELL DEFINING A REFINING CHAMBER, MEANS IN SAID SHELL FORMING AN INLET CHAMBER AND AN OUTLET CHAMBER ON OPPOSITE SIDES OF SAID REFINING CHAMBER, A ROTOR MOUNTED FOR ROTATION IN SAID SHELL AND INCLUDING A ROTOR BODY EXTENDING THROUGH SAID REFINING CHAMBER, SAID ROTOR BODY HAVING THEREON AT LEAST TWO CIRCUMFERENTIAL ROWS OF SUBSTANTIALLY UNIFORM AND UNIFORMLY SPACED TEETH FORMING WORKING SURFACES, SAID TEETH IN SAID ROW NEAREST SAID INLET CHAMBER BEING OF SUBSTANTIALLY GREATER DEPTH AND SPACING THAN SAID TEETH IN SAID ROW NEAREST SAID OUTLET CHAMBER TO PROVIDE A CORRESPONDINGLY GREATER NUMBER OF TEETH IN SAID ROW NEAREST SAID OUTLET CHAMBER, SAID SHELL HAVING THEREON ROWS OF TEETH SUBSTANTIALLY COMPLEMENTARY TO AND IN RADIALLY SPACED AND OVERLYING RELATION WITH SAID TEETH ON SAID ROTOR BODY TO DEFINE THEREWITH A CORRESPONDINGLY PLURALITY OF STEPPED WORKING ZONES FOR THE STOCK PASSING FROM SAID INLET CHAMBER TO SAID OUTLET CHAMBER, AND SAID TEETH AND THE GROOVES THEREBETWEEN IN EACH OF SAID ROWS EXTENDING SUBSTANTIALLY PARALLEL WITH THE AXIS OF ROTATION OF SAID ROTOR TO MINIMIZE THE PUMPING ACTION OF SAID APPARATUS AND TO EFFECT A SUBSTANTIALLY UNIFORM RATE OF AXIAL TRAVEL OF THE STOCK WITH RESPECT TO EACH OF SAID ZONES. 